Conventional beef is the most common food containing added growth hormones in the United States. Several other animal products carry either added or naturally occurring hormones, though the amounts vary widely. Here’s a practical breakdown of which foods contain growth hormones, which don’t, and what the levels actually mean for your body.
Beef: The Primary Source of Added Hormones
The FDA has approved a long list of hormone implants for use in beef cattle. These implants are placed under the skin of the ear and slowly release hormones that help cattle gain weight faster and more efficiently. The approved hormones fall into two categories: natural hormones like estradiol, progesterone, and testosterone, and synthetic versions like trenbolone acetate and zeranol. The FDA currently lists over two dozen approved implant products for different classes of beef cattle, from young calves to finishing steers and heifers.
All beef, whether from treated or untreated cattle, contains naturally occurring steroid hormones. Bulls produce higher levels of testosterone, while steers tend to have more cortisol and pregnenolone. Implanted cattle produce meat with slightly more estrogen than untreated animals: about 1.9 nanograms per 3-ounce serving compared to 1.3 nanograms. That difference of 0.6 nanograms is tiny in practical terms. A child’s body naturally produces around 50,000 nanograms of estrogen per day, and a non-pregnant adult woman produces roughly 480,000 nanograms daily. The amount in a serving of beef, even from an implanted animal, is a fraction of what your body already makes.
Dairy Milk and rBGH
Some dairy cows in the U.S. are treated with recombinant bovine growth hormone (rBGH, also called rBST), a synthetic version of a hormone cows naturally produce. It stimulates milk production. A 2014 USDA survey found that fewer than 1 in 6 cows (about 15%) were being injected with rBGH, and that number has likely continued to decline as major retailers and dairy brands have moved away from it due to consumer pressure.
Bovine growth hormone itself is a protein that gets broken down during digestion, so it doesn’t function as a hormone in the human body. The bigger concern researchers have raised is that rBGH-treated cows produce milk with higher levels of insulin-like growth factor 1 (IGF-1), a hormone that does have biological activity in humans. That said, pasteurization reduces IGF-1 levels, and the amounts remaining in milk are small relative to what your body produces on its own.
Chicken, Turkey, and Pork Have No Added Hormones
Federal regulations prohibit the use of growth hormones in raising poultry and hogs. This is a blanket ban, not a voluntary choice by producers. If you see “no hormones added” on a package of chicken, turkey, or pork, the label is required by the USDA to also include a disclaimer stating that federal regulations prohibit hormone use in those animals. In other words, every chicken and pork product sold in the U.S. is hormone-free by law, so the label is more of a marketing reminder than a meaningful distinction between brands.
Poultry and pigs do, of course, contain naturally occurring hormones produced by the animals’ own bodies. These are present in small amounts in all animal tissue and are not the result of any added treatment.
Farmed Fish and Hormone Use
Growth hormones are not approved for use in fish farming in the United States. However, in some countries, particularly in parts of South and Southeast Asia, steroid hormones like testosterone are used in aquaculture. The most widespread practice involves treating tilapia with testosterone early in life to produce all-male populations, since male tilapia grow larger and faster. Farmers in these regions have also used hormones in carp species to boost growth rates.
Research on farmed fish from markets in Bangladesh found testosterone and progesterone residues in samples of rui, catla, and tilapia, with some exceeding acceptable daily intake levels. Estrogen residues were also detected in rui and catla samples, though not in tilapia. If you eat imported farmed fish, the source country and its regulatory standards matter. Domestically farmed fish in the U.S. and EU are not treated with growth hormones.
Soy and Phytoestrogens Are Not Growth Hormones
Soy products contain isoflavones, which are plant compounds that can weakly mimic estrogen in the body. These are sometimes called phytoestrogens, which leads to confusion about whether soy “contains hormones.” Isoflavones are not growth hormones and do not function the same way as the steroid hormones used in cattle production.
Earlier concerns about soy disrupting hormonal development were based primarily on animal studies. Human data tells a different story. Systematic reviews have found no significant link between soy consumption and early puberty, hormonal disruption, or estrogen-like effects in children or adults. Long-term studies of children fed soy-based infant formulas showed no evidence of abnormal pubertal timing, gynecomastia, or changes in bone metabolism markers, even though those infants had higher circulating levels of isoflavones. Chickpeas and lentils also contain phytoestrogens, though in lower concentrations than soy.
How U.S. and EU Rules Differ
The European Union banned synthetic growth hormones in livestock in 1985 and restricted natural hormones to therapeutic purposes only. Imports of hormone-treated beef into the EU are also prohibited. The EU’s position is rooted in the precautionary principle: the idea that a technology should be proven safe before approval, rather than assumed safe until proven harmful.
The U.S. takes the opposite approach. The FDA, USDA, and the National Cattlemen’s Beef Association maintain that FDA-approved hormones in beef pose no proven health risks. American regulators consider the EU ban scientifically unjustified, while the EU has argued before the World Trade Organization that member nations have the right to set their own level of health protection, even based on minority scientific views. This disagreement has been an active trade dispute for decades.
What Labels Actually Tell You
If you want to avoid added hormones in beef and dairy, look for products labeled “USDA Organic.” Organic certification requires that animals are raised without synthetic hormones or growth promoters. To carry the “organic” label, a product must contain at least 95% organically produced ingredients by weight.
The label “no hormones added” on beef or dairy means the producer has provided documentation to the USDA showing that hormones were not used. On chicken, turkey, or pork, that same label is essentially meaningless since hormones are already banned in those animals. “Grass-fed” does not automatically mean hormone-free, as grass-fed cattle can still receive hormone implants unless the product also carries an organic or no-hormones-added claim.
For imported seafood, there is no widely used label indicating hormone-free status. Buying domestically farmed or wild-caught fish is the most reliable way to avoid hormone-treated seafood.